Co-C bond dissociation energy and reaction volume change of 2',5'-dideoxyadenosylcobalamin studied by laser-induced time-resolved photoacoustic calorimetry

Time resolved photoacoustic calorimetry (PAC) was applied to a study of the photolysis of a coenzyme B(12) analog 2',5'-dideoxyadenosylcobalamin, which lacks an -OH group at the 2' position of ribofuranose ring. In aqueous solution, we report for the first time the quantum yield Phi(d) (0.25+/-0.02), Co-C bond dissociation energy (BDE; 31.8+/-2.5 kcal mol(-1)) and reaction volume change deltaV(R) (6.5+/-0.5 ml mol(-1)) due to conformation changes of the corrin ring and its side chains accompanying the cleavage of the Co-C bond. These values for the analog are very similar to those for the natural cofactor. Based our results and previous studies, a possible explanation for the similarity in their structure and properties versus the large difference in their enzymatic activity is discussed.     

Racemization of chiral amino alcohols III: Effect of Mg or Ca addition on the activity and stability of the Co/γ-Al2O3 catalyst

The racemization of R-(-)-2-amino-1-butanol in a reaction using Co/γ-Al₂O₃ catalysts and catalysts modified by Mg or Ca was investigated in this paper. Complete racemization was achieved with a yield of over 83% at using the Mg modified Co/γ-Al₂O₃ catalyst under optimized reaction conditions of 170°C and 2.5 MPa of H₂. The catalysts were thoroughly characterized by XRD, XPS, TPR, SEM and TEM. The addition of Mg and Ca may be advantageous for dispersing and stabilizing the active species of the Co/γ-Al₂O₃ catalyst, protecting from sintering, significantly improving its catalytic activity and stability.     

The embedding of meta-tetra(hydroxyphenyl)-chlorin into silica nanoparticle platforms for photodynamic therapy and their singlet oxygen production and pH-dependent optical properties

This study relates to nanoparticle (NP) platforms that attach to tumor cells externally and only deliver singlet oxygen for photodynamic therapy (PDT) while conserving the embedded photosensitizers (PS). As a model, we demonstrate the successful embedding of the PS meta‐tetra(hydroxyphenyl)‐chlorin (m‐THPC) in NP that are based on a sol–gel silica matrix and also show its positive effect on the singlet oxygen production. The embedding of m‐THPC inside silica NP is accomplished by a modified Stöber sol–gel process, in which (3‐aminopropyl)‐triethoxysilane is introduced during the reaction. Singlet oxygen delivery by the targetable photodynamic NP exceeds that from free PS molecules. In the physiological pH range, there is no significant pH‐induced decrease in the fluorescence of m‐THPC embedded in silica NP, which might otherwise affect the efficiency of PDT.     

基于模糊理论的空间屏蔽滤波信号去噪

基于模糊理论提出了一种空间屏蔽滤波信号去噪方法.对信号进行二进小波变换后,对信号进行空间屏蔽滤波,对于未通过滤波器的系数进行模糊阈值处理实现去噪.通过对含噪HeaviSine和Doppler信号的去噪仿真,表明,该方法对噪音具有良好的抑制作用,能较好地保持信号在间断点处的信息.与传统空间屏蔽滤波相比,该方法对不同种类的含噪信号均具有良好的去噪效果.     

金属组学在急性心肌梗死早期诊断的应用

为探讨急性心肌梗死(AMI)患者血清中K⁺、Na⁺、Ca²⁺、Fe²⁺、Mg²⁺含量变化,并研究其与心肌梗死患者之间的关系。选取2022年5月至2023年2月收治的AMI患者37例,同时选取健康体检者35例作为对照组。依据入院时或体检时收集的抽血样本进行临床生化分析,比较两组间血清K⁺、Na⁺、Ca²⁺、Fe²⁺、Mg²⁺含量,采用判别方程、主成分分析法(PCA),判断分析哪种金属离子对于心肌梗死的诊断价值大。结果表明,AMI患者的血清中Ca²⁺和Fe²⁺含量低于健康对照组,差异具有统计学意义。基于血钙、铁水平两组具有显著性差异,以它们为基础进行判别分析,获得判别函数式。将血清中K⁺、Na⁺、Ca²⁺、Fe²⁺、Mg²⁺     

全自动高温水解-离子色谱法测定氧化镧铈中氟、氯

为探究稀土氧化物中氟(F)和氯(Cl)元素含量的快速检测方法,通过全自动高温水解仪对氧化镧铈样品进行前处理,并利用氢氧根体系离子色谱仪检测吸收液中F-、Cl-离子的含量,建立了基于全自动高温水解-离子色谱法测定氧化镧铈中的F、Cl元素含量的快速检测方法,该方法有效避免了传统前处理方法过程复杂、分析时间慢、极易受人为干扰的问题。称取0.3g氧化镧铈样品,在氧气流量为300 mL/min,1100 ℃高温下水解燃烧20 min,吸收定容为体积20mL的吸收液,以NAOH(15mmol/L)作为淋洗液,经色谱柱分离,测得F-与Cl-在质量浓度为1.00 mg/L-15.00 mg/L范围内,质量浓度与离子色谱峰面积呈线性关系,相关系数均为0.9999。检出限分别为0.003mg/L和0.12mg/L。全自动高温水解仪联用离子色谱仪检测系统对氧化镧铈中F-的平均加标回收率测定结果为98.4%,标准偏差RSD为0.94%;对Cl-的加标回收率测定结果为97.8%,RSD为2.86%。说明该方法较高准确度及精密度,测试结果准确可靠满足企业和检测机构的测试需求,为稀土氧化中氟、氯元素含量的研究及相关产品的开发提供了理论基础。     

飞行器上层大气层空气动力特性探讨

针对近地轨道飞行器所面临的上层大气层(100～300 km)空气动力学问题,对几类典型航天器构型的上层大气层气动力特性进行了分析,给出了典型气动布局在该空域的气动力基本规律,取得了对上层大气层气动力关键影响因素的初步认识.在上层大气层,飞行器的绕流属于自由分子流状态.研究发现,气体分子与不同材质物面的相互作用反映出截然...     

PTC: Full and Drift Particle Orbit Tracing Code for α Particles in Tokamak Plasmas

Fusion born α particle confinement is one of the most important issues in burning plasmas,such as ITER and CFETR.However,it is extremely complex due to the nonequilibrium characteristics,and multiple temporal and spatial scales coupling with background plasma.A numerical code using particle orbit tracing method(PTC)has been developed to study energetic particle confinement in tokamak plasmas.Both full orbit and drift orbit solvers are implemented to analyze the Larmor radius effects on α particle confinement.The elastic collisions between alpha particles and thermal plasma are calculated by a Monte Carlo method.A triangle mesh in poloidal section is generated for electromagnetic fields expression.Benchmark between PTC and ORBIT has been accomplished for verification.For CFETR burning plasmas,PTC code is used for α particle source and slowing down process calculation in 2D equilibrium.In future work,3D field like toroidal field ripples,Alfven and magnetohydrodynamics instabilities perturbation inducing α particle transport will be analyzed.     

Characterization of Roasting Time on Sensory Quality,Color, Taste,and Nonvolatile Compounds of Yuan An Yellow Tea

Roasting is crucial for producing Yuan An yellow tea (YAYT) as it substantially affects sensory quality. However, the effect of roasting time on YAYT flavor quality is not clear. To investigate the effect of roasting time on the sensory qualities, chemical components, odor profiles, and metabolic profile of YAYTs produced with 13 min roasting, 16 min roasting, 19 min roasting, 22 min roasting, and 25 min roasting were determined. The YAYTs roasted for 22 min got higher sensory scores and better chemical qualities, such as the content of gallocatechin (GC), gallocatechin gallate (GCG), free amino acids, solutable sugar, meanwhile the lightness decreased, the hue of tea brew color (b) increased, which meant the tea brew got darker and yellower. YAYTs roasted for 22 min also increased the contents of key odorants, such as benzaldehyde, nonanal, β-cyclocitral, linalool, nerol, α-cedrol, β-ionone, limonene, 2-methylfuran, indole, and longiborneol. Moreover, non-targeted metabolomics identified up to 14 differentially expressed metabolites through pair-wise comparisons, such as flavonoids, phenolic acids, sucrose, and critical metabolites, which were the main components corresponding to YAYT roasted for 22 min. In summary, the current results provide scientific guidance for the production of high quality YAYT.     

A Novel Gelatin-Based Sustained-Release Molluscicide for Control of the Invasive Agricultural Pest and Disease Vector Pomacea canaliculata

Pomacea canaliculata, one of the 100 most destructive invasive species in the world, and it is an important intermediate host of Angiostrongylus cantonensis. The molluscicides in current use are an effective method for controlling snails. However, most molluscicides have no slow-release effect and are toxic to nontarget organisms. Thus, these molluscicides cannot be used on a large scale to effectively act on snails. In this study, gelatin, a safe and nontoxic substance, was combined with sustained-release molluscicide and was found to reduce the toxicity of niclosamide to nontarget organisms. We assessed the effects of gelatin and molluscicide in controlling P. canaliculata snails and eggs. The results demonstrated that the niclosamide retention time with 1.0% and 1.5% gelatin sustained-release agents reached 20 days. Additionally, the mortality rate of P. canaliculata and their eggs increased as the concentration of the niclosamide sustained-release agents increased. The adult mortality rate of P. canaliculata reached 50% after the snails were exposed to gelatin with 0.1 mg/L niclosamide for 48 h. The hatching rate of P. canaliculata was only 28.5% of the normal group after the treatment was applied. The sustained-release molluscicide at this concentration was less toxic to zebrafish, which means that this molluscicide can increase the safety of niclosamide to control P. canaliculata in aquatic environments. In this study, we explored the safety of using niclosamide sustained-release agents with gelatin against P. canaliculata. The results suggest that gelatin is an ideal sustained-release agent that can provide a foundation for subsequent improvements in control of P. canaliculata.